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Airborne algae as a wood degradation factor
1992 - IRG/WP 92-1549
The occurrence of airborne (aerophytic) algae on wood is a very frequent phenomenon. However, there is currently a lack of information concerning their effect on the wood tissue. Some important genus of algae infesting wood under natural conditions are listed, as well as the results of experimental studies in the "in vitro" culture concerning the effect of two selected algal species on some physico-mechanical properties and on the structure of beech and Scots pine woods.
K J Krajewski, J Wazny

Antifungal properties of new quaternary ammonium and imidazolium salts against wood decay, staining and mould fungi
2004 - IRG/WP 04-30347
The biological activity of twenty-four potential wood preservatives – imidazolium and quaternary ammonium salts with a modified anion structure was determined employing screening agar-plate and agar-block methods. Experiments were carried out on Scots pine (Pinus sylvestris L.) wood. The aim of the performed studies was to investigate the effect of structure modification of IC and QAC with organic anions or copper (ll) and zinc complexes on their biological activity against wood decay, staining and mould fungi. The fungicidal value of new compounds for Coniophora puteana ranged from 0.64 kg/m3 to 2.2 kg/m3. Aspergillus niger turned out to be the most resistant fungus to the action of modified IC and QACs, whereas Sclerophoma pityophila was effectively inhibited by the examined salts. The performed soil-block tests showed that the IC and QAC were leached from the experimental wood in conditions of contact with moist soil and revealed their fungal detoxification by mould fungi, especially by Gliocladium roseum. Observations made using the scanning electron microscope of the colonization and decay of treated wood by mould fungi confirmed tolerance of mould fungi to QACs.
J Zabielska-Matejuk, W Wieczorek

The preliminary characterization of ß-1,4-xylanase of the brown-rot fungus Gloeophyllum trabeum
1990 - IRG/WP 1447
The extracellular ß-1,4-xylanase of the brown-rot fungus, Gloeophyllum trabeum, was isolated from crude extract by chromatofocusing method (PBE 94 column chromatography). The isoelectric point was estimated to 4.2-4.8 by cromatofocusing and 4.5 by isoelectric focusing (IEF). The molecular weight of the enzyme was estimated to 37,000 dalton by SDS-PAGE. The optimal temperature for the crude extract xylanase was +70°C. The enzyme stability, after 1 h incubation, decreased sharply above +60°C and pH 6.
A-C Ritschkoff, M Rättö, L Viikari

Biodegradation of creosote/naphthalene-treated wood in the marine environment
1977 - IRG/WP 428
The present study was undertaken to determine the biodegradability of marine grade creosote and selected components, including naphtalene, and to determine the effectiveness of (up to 40%) creosote in protecting wood from microbial attack. Also, the impact(s) of creosote and naphtalene-enriched creosote on the microbial ecology os estuarine environments was examined.
P A Seesman, R R Colwell, A Zachary, A J Emery

Lignin degradation by wood-degrading fungi
1986 - IRG/WP 1310
The wood-degrading white-rot fungus Phanerochaete chrysosporium, has been the subject of intensive research in recent years and, based upon isolation of the extracelluar enzyme ligninase, major advances have now been made toward elucidating the mechanism by which this fungus degrades lignin. From these developments, a model emerges which could explain the process by which wood-degrading fungi in general, attack lignin.
P J Harvey, H E Schoemaker, J M Palmer

Biodegradation of acetylated southern pine and aspen composition boards
1994 - IRG/WP 94-40020
This objective of this study was to investigate the influence of the acetylation treated wood fiber, Phenol-formaldehyde resin content level, two wood fiber species, three fungi species on the dimensional stability and decay resistence of high density composition boards. A standard ASTM method was used to evaluate weight loss and thickness change. The linear shrinkage and expansion of each species were also determined. All specimens were exposed to decay chambers for 16 weeks. Test results indicated that most of the main factors significantly influence the thickness and length changes and the decay resistance of the high density composition boards.
P Chow, T Harp, R Meimban, J A Youngquist, R M Powell

Acetylation of lignocellulosic materials
1989 - IRG/WP 3516
A simplified procedure for the acetylation of lignocellulosic materials has been developed. The acetylation is done with a limited amount of liquid acetic anhydride without the addition of a catalyst or an organic co-solvent. Dimensional stability and biological resistance are both much improved by the acetylation. Equilibrium moisture content in acetylated material is considerably lower than in unmodified material. No reduction of bending strength was found for acetylated solid wood samples. The process can be employed for both fibers, wood particles and solid wood. The process is applicable to hardwoods and softwoods, including solid spruce wood, and to non-wood fibers such as jute.
P Larsson, A-M Tillman

The fungal degradation of quaternary ammonium compounds in wood
1998 - IRG/WP 98-10263
This work focuses on the biodegradation of didecyldimethylammonium chloride (DDAC) by the mould fungus Gliocladium roseum within a woody matrix. Three sawdust types, distinguished by their treatment and amount of DDAC retained, were inoculated with the fungus and their DDAC loss was measured over 11 weeks. The rates of degradation varied depending on the sawdust; however, a significant loss of DDAC was observed for all three. A metabolic by-product coincided with the fungal degradation of DDAC. The metabolite was separated using preparative HPLC and identified by proton-NMR and infrared spectroscopy to be a hydroxylated QAC.
J W Dubois, J N R Ruddick

Biochemical relationships between biodegradation of cellulose and formation of oxalic acid in brown-rot wood decay
1991 - IRG/WP 1472
Non-enzymic hydrolysis of cellulose with low concentrations of oxalic acid was examined. The incubation of pine wood pulp with 1% oxalic acid (pH 1.3) at 35°C for 4 weeks reduced the original viscosity to 60%. Reducing sugars were liberated from various cellulosic samples by the oxalic acid treatment. However, crystallinities of cellulose in those samples did not change before and after the treatments. Then, the enzymatic formation of oxalic acid was investigated in relation to cellulose biodegradation by brown-rot fungi. We succeeded in isolating oxaloacetase from the brown-rot fungus Tyromyces palustris in cell-free extracts which catalyze hydrolysis of oxaloacetate to produce oxalate and acetate. During the brown-rot wood decay process, oxaloacetase may play an important role in degradation of wood carbohydrate.
M Shimada, Y Akamatsu, A Ohta, M Takahashi

Biodegradation of wood in wet environments: A review
1997 - IRG/WP 97-10217
Wood in wet environments is attacked and degraded by soft rot fungi and erosion and tunnelling bacteria, which are more tolerant to high moisture and reduced oxygen conditions than basidiomycetes, such as white and brown rot fungi. Since basidiomycetes are normally more aggressive and can degrade wood faster than soft rot fungi and bacteria wood in wet environments can survive longer. In fact, archaeological investigations have shown that wood buried deep in ocean sediments have survived relatively intact for hundreds and even thousands of years. In this review degradation patterns of various types of microbial wood decay have been briefly described, and then examples of decay type(s) present in wood exposed in various wet environments are presented. Concluding remarks emphasise the importance of understanding the relationship between the conditions of wet environments and the biological wood decay present for prolonging the life of wood in service and properly restoring wooden artefacts of historical value.
A P Singh, Yoon Soo Kim

Isolation of soil borne bacteria and fungi from treated timber
2001 - IRG/WP 01-50174
Most research in the last few decades has focused on the development of new strategies to control biological attack and the means to quantify this. Comparatively little work has been done to examine the effect that treated timber might have on its surrounding environment. This presentation will describe a methodology that attempts to detect any changes which might occur in the soil microflora following the introduction of timber treated with a number of chemical agents containing organic active ingredients (a.i.). It was also the purpose to isolate organisms that can break down organic a.i.. A technique was developed to determine whether the presence and nature of a timber preservative influenced the size and composition of a microbial population that colonised timber when buried in soil. Samples of treated timber were incubated in a solution eluted from soil that contained a diverse, viable microbial population. After incubation, the size and composition of the microflora both in the eluate and adhering to the timber was examined.
I Stephan, A Stegemann, G Heidrich

Enhanced biodegradation of cocopeat by soft rot fungi
1998 - IRG/WP 98-10276
Biodegradation of cocopeat (coir dust) was enhanced by the addition of nitrogen (N) fertilizer and inoculation with the soft rot fungus Chaetomium globosum. The N and fungally treated cocopeats had a greater percentage weight loss (27%) after 3 months compared with 7% weight loss without the added fungi and N fertilizer. In addition, their hemicellulose, cellulose and lignin contents were greatly reduced. The decay patterns examined by light microscopy were typical of soft rot and included cavity formation. A bioassay using cress (Lepidium sativum L.) showed that root growth was inhibited by raw cocopeat extracts. This inhibitory effect was virtually eliminated in extracts from the biodegraded cocopeat. This suggests that the 'composted' cocopeat appeared sufficiently mature for use as a horticultural substrate after 3 months of biodegradation.
P Y Yau, R J Murphy

Confocal Laser Scanning Microscopy (CLSM) of decayed wood
1998 - IRG/WP 98-10273
Confocal laser scanning microscopy (CLSM) is currently being used to examine biodegraded wood and is proving to be a useful new technique in this area of work. Non-invasive optical sectioning within a thick specimen (20 - 50 µm), coupled with post image processing techniques allows manipulation of images and 3-D reconstruction from serial sections. Glutaraldehyde can cause cell autofluorescence, and since wood cell components do not react with it, a relatively simple technique for localising fungal hyphae, using glutaraldehyde as a fixative, was developed. Subsequent use of probes specific for chitin provided superior images of fungal hyphae in wood. High resolution, sequential, 2-D images can be produced to determine the mode of fungal attack within a thick wood specimen in a dynamic way. Voxel 3-D reconstruction of a series of image stacks enabled stereo viewing of objects.
Ying Xiao, R N Wakeling, A P Singh

Aspects of the fungal degradation of quaternary ammonium compounds in liquid culture
1997 - IRG/WP 97-30160
Didecyldimethylammonium chloride (DDAC) is a quaternary ammonium compound (QAC) that has found use as an anti-sapstain preservative for the transportation of softwood lumber from Canada to overseas markets. However, its use is limited by the knowledge that certain mould fungi seem capable of degrading it. The aim of this research was to gain knowledge about the fungal degradation of DDAC. The effects of Verticillium bulbillosum - a demonstrated QAC-degrading mould - on DDAC within a defined liquid culture were studied. Interactions between the liquid medium and DDAC; the degree of fungal tolerance under varying conditions; and rate of degradation paralleled with fungal growth were examined.
J W Dubois, J N R Ruddick

Bioremediation of surfactant contaminated waste
1996 - IRG/WP 96-50070
The objective of this work was to determine the potential of fungi as agents for the bioremediation of wastes (particularly wood and soil) contaminated with quaternary ammonium compounds (QACs). Until now only bacteria have been investigated for this purpose. Tolerant strains of Gliocladium roseum and Verticillium bulbillosum were studied for their ability to degrade the following QACs: didecyldimethylammonium chloride, cocoalkyltrimethylammonium chloride, and dicocodimethylammoium chloride. Preliminary experiments were used to determine the toxic threshold concentrations for selected QACs in solid and liquid media. As solid media, wood and soil were treatet with the different QACs and inoculated with one of the fungi. After a pre determined incubation period, the QAC was extracted from the wood and soil samples and the loss of chemical was measured by HPLC using an indirect photometric detection. Both fungi were able to degrade considerable amounts of all QACs tested under the experimental conditions.
J L Bürgel, J Dubois, J N R Ruddick

Fungal siderophores and their rôle in wood biodegradation
1990 - IRG/WP 1442
Iron and other metals such as manganese, play an important role in the metabolic functions of fungi that cause wood deterioration. These transition metals are also found in, or associated with, the extracellular fungal enzymes shown to be directly involved in the decay process. Recently our research group was able to show that siderophores (low molecular weight biological chelators) are produced by both brown and white rot fungi. These siderophores may function to scavenge transition metals for fungal metabolism and extracellular enzyme production. In addition, our preliminary work with the purified siderophores suggests that these compounds may play a more direct role in lignin modification, similar to that reported by other researchers investigating the properties of 'biomimetic' structures. Because of the low molecular weight of the siderophore-metal complex (500-1000 daltons), and the oxidizing potential of the bound transition metals, certain siderophore structures could also play a potential role in early stages of cellulose depolymerization by brown rot fungi. Developing a better understanding of the action of fungal siderophores, their role in scavenging metals for fungal metabolism, and their possible function directly in lignocellulose degradation, will help us to better understand how wood degradation occurs.
J Jellison, B Goodell, F Fekete, V Chandhoke

Micromorphology of decay in Keruing heartwood by the basidiomycetes Phellinus contiguus and Dacrymyces stillatus
2002 - IRG/WP 02-10454
This study aimed to characterise the micromorphology of fungal decay in a wooden handrailing in an above ground exposure at the Thames embankment in London. Keruing heartwood (Dipterocarpus spp.) was determined as the construction timber and the two basidiomycetes Phellinus contiguus and Dacrymyces stillatus identified as main decay organisms. Their decay patterns within Keruing heartwood were studied using light microscopy. Besides typical white and brown rot decay features the analysis also revealed cavities in the fibre S2 wall layers. A laboratory screening test with monocultures of both fungi confirmed their individual ability to form rhomboidal shaped cavities similar to those commonly associated with “true” soft rot fungi. This form of attack indicates that typical soft rot-like cavities can also be formed by white and brown rotting basidiomycetes facultatively and are therefore not an absolute indication for the occurrence of soft rot causing asco- and deuteromycetes respectively.
G Kleist, M Ray, R J Murphy

Evidence for actinomycete degradation of wood cell walls
1990 - IRG/WP 1444
Several unique patterns of degradation occurring in wood cell walls have been observed in wooden stakes inserted in unsterile soil in the laboratory. Some of the patterns have also been observed in coniferous wood taken from forest floors. All the observed attack types occur within wood cell walls, mainly within the S2 layer. Attack is characterised by channels of varying diameter or small fusiform cavities arranged in the form of a rosette. Some channels are narrow, 0.5-1.0 µm, and form a highly branched network. Other channels are wider, up to approx. 2-3 µm and less branched. All channels are produced by hyphae growing within the wood cell walls. Attack has been observed to arise from the branching of thin hyphae growing longitudinally in the fibre lumina. The small diameter of the hyphae and the fact that these decay patterns have not been described for wood degrading fungi indicate that actinomycetes may be responsible.
T Nilsson, G F Daniel, S L Bardage

The production of extracellular hydrogen peroxide by some brown-rot fungi
1990 - IRG/WP 1446
The role of hydrogen peroxide (H2O2) has been discussed in the degradation of wood by wood-rotting fungi. The production of extracellular hydrogen peroxide was studied by detecting the oxidation of the chromogen 2,2'-azinobis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) by H2O2 and horse radish peroxidase (HPR). ABTS and HPR were added to a solid wood based culture media. In this study two brown-rotters, Poria placenta and Serpula lacrymans, produced detectable extracellular hydrogen peroxide.
A-C Ritschkoff, L Paajanen, L Viikari

The effects of preservative treatment and exposure to wood degrading fungi on fiber reinforced polymer (FRP) materials used for structural wood reinforcement
2001 - IRG/WP 01-40204
Glass fiber reinforced phenolic (GFRP) composite materials are becoming increasingly accepted for use in the construction industry because they combine advantages of both wood and advanced polymeric materials. Addition of only 1-3% FRP in the tension zone, for example, can typically improve the strength of the hybrid system by 200%. As more applications are found for wood/FRP hybrids, (e.g. laminated wood for bridge applications, waterfront piers) their use in exterior and high-decay-hazard environments would be expected to grow. Since FRPs were designed to be used with wood material for use in exterior exposures, they will be exposed wood preservative chemicals, and to wood decay fungi as well. Therefore, currently developed glass-fiber reinforced phenolic polymer materials for wood reinforcement were examined to determine the effects of wood preservative chemicals and exposure to wood degrading fungi. Several common wood preservative chemicals (oil-and water-borne) were used for treatment of FRP materials. While chemically "fixing" preservatives resulted in significant strength loss, oil-borne preservatives systems did not affect the mechanical properties of the FRP material. When the common brown and white rot fungi (Gloeophyllum trabeum and Trametes versicolor) were used for fungal exposure studies, after 24 weeks of exposure G. trabeum exposed FRP coupons showed reduction in interlaminar shear strength. Scanning electron microscopy (SEM) and fluorescent photomicrograph 58 analysis supported the mechanical test results, indicating that fungal growth and possible consumption of organic sizing material on the wood/fiber interface had occurred. Further studies are underway with different organisms to provide a more detailed explanation of biodegradation mechanisms of FRP composites for wood reinforcement.
C Tascioglu, B Goodell

Development and Implementation of a DNA – RFLP Database for Wood Decay and Wood Associated Fungi
2004 - IRG/WP 04-10527
We are developing Restriction Fragment Length Polymorphism (RFLP) and Internal Transcribed Spacer (ITS) sequence databases for wood decay basidiomycetes and other fungi associated with wood. These databases currently house information for 39 fungal species consisting of 9 brown-rot basidiomycetes, 12 white rot basidiomycetes, 1 soft rot, 1 stain fungi, and 16 molds or other ascomycetes or imperfect fungi. We plan to add 6 brown rot, 14 white rot and 8 other species that we have in culture by summer 2004. Using the RFLP database, we were able to identify wood decay basidiomycetes that were isolated from a local forest and that could not be distinguished based on morphology. In addition, RFLP data confirmed identifications of several other wood associated fungi. One of our ultimate goals is to establish a web-based database of wood basidiomycetes and wood-associated fungi emphasizing ITS sequence and RFLP pattern data plus morphological characteristics in one searchable system. These databases will be able to provide sensitive and reliable identifications of the wood decay community and important wood decay fungal species.
S V Diehl, T C McElroy, M L Prewitt

Nondestructive assessment of biodegradation in southern pine sapwood exposed to attack by natural populations of decay fungi and subterranean termites
1994 - IRG/WP 94-20042
Field methods for evaluating decay resistance of experimentally treated materials lack a means for quantitative measurement of residual strength. Quantitative relationships between speed of impact-induced waves travelling parallel to the grain and residual compressive strength have been demonstrated in softwood attacked by brown rot-decay fungi, but the effects of termites have not been documented. We tested southern pine sapwood stakes that were vertically inserted for one-half their length in soil in a southern pine forest in southern Mississippi. The results showed that measurement of both speed and attenuation of a reciprocating impact-induced wave will yield quantitative information on extent of total biodegradation in southern pine sapwood, independent of organism causing the damage.
R C De Groot, R J Ross, W Nelson

Screening of fungal strains for wood extractive degradation
1998 - IRG/WP 98-10254
Fungal strains were screened for their ability to degrade apolar extractives in wood from scots pine. The degradation of total wood extractives by 91 different strains was monitored in stationary batch assays incubated for 6 weeks. The results obtained show that the ability of wood-inhabiting fungi to utilize wood extractives varied greatly, even for different isolates of the same species. Fungal pretreatment provided up to 70% total resin reduction. Outstanding strains included mainly white-rot fungi. Several sapstain strains were also efficient extractive degraders. Apolar extractives are well known for their inhibitory effect to fungal growth. However, our findings show that wood extractives can serve as carbon source for numerous wood-inhabiting fungi. Furthermore, these results indicate the potentials of wood-inhabiting fungi in biotechnological processes for pulp and paper manufacturing, ie., wood chip depitching and biodetoxification.
J Dorado, M J Martinez-Inigo, T A van Beek, F W Claassen, J B P A Wijnberg, R Sierra-Alvarez

Production of monoclonal antibodies to fungal metabolites
1986 - IRG/WP 1306
The role of fungal extracellular enzymes in wood biodegradation is incompletely understood. Our lab is beginning a project utilizing monoclonal antibodies to characterize extracellular metabolites of the brown rot fungus Poria placenta Fr. (Cooke). Monoclonal antibody technology takes advantage of the ability of antibody secreting spleen cells from immunized mice to fuse in the presence of polyethylene glycol (PEG) with myeloma cells, which do not produce antibodies but do have the ability to grow in culture. The resultant hybrid cell or hybridoma has the capacity to produce antibodies of predetermined specificity and to grow "immortally" in culture. These hybridomas can be grown on a selective media, cloned, and the highly specific antibodies they produce purified. Monoclonals can be produced to fungal enzymes or other metabolites of interest. Monoclonal antibodies are capable of being more specific for a particular antigen than polyclonal antibodies because each B-lymphocyte (removed from the spleen) produces only one specific antibody to an antigen fraction. In our research, injection of extracellular fungal filtrates into an animal presents the immune system with a variety of antigen sites to produce antibodies to not only the target antigen (a glucosidase, for example) but also to extraneous materials injected with the extracellular filtrate. Two approaches exist to implement production of antisera to the desired antigen. One is to purify the antigen prior to injection. This solution has obvious advantages but it also has disadvantages.
J Jellison, B Goodell

Inhibition of the biodegradation of coniferous and broadleaved wood by new imidazolium salts
2003 - IRG/WP 03-30320
Studies were carried out on fungicidal values of fourteen potential wood preservatives – modified quaternary heteroaromatic compounds using the screening agar-block. The vacuum treated blocks (22mm x 17mm x 12mm) of Scots pine (Pinus sylvestris L.), spruce (Picea excelsa L.), beech (Fagus silvatica L.) and birch (Betula verrucosa Ehrh.) with testing compounds were exposed to Coniophota puteana and Trametes versicolor for 4 and 6 weeks. The part of treatment samples was leached according to EN 84, then the toxic value and degree of leaching from wood of compounds were determined. The optimal fungicidal activity against Coniophora puteana was observed for imidazolium salts with linear hydrophobic substituents (1.1 kg/m3 - !.6 kg/m3). The aromatic substituents reduced the toxic activity of studied chlorides. The imidazolium propionates were less effective then chlorides with the same cations structure. The investigated compounds were well good fixed in the wood of Scots pine, leaching coefficient was from 1.0 to 1.6. The toxic value against Chaetomium globosum (investigated by block-perlite method) of two imidazolium chlorides with linear alkoxymethyl substituents was 3.5 times less (5.5 kg/m3) then against brown rot fungi Coniophora puteana (1.1 kg/m3). The observation using scanning electron microscope of colonization and decaying of treated wood by testing fungi were confirmed obtained toxicometric results of new, potential wood preservatives.
J Zabielska-Matejuk, J Pernak, W Wieczorek

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